[Elecraft] S-Meter Calibration

[kc4kgu@ENTERZONE.NET]

On Mon, 11 Feb 2002, George, W5YR wrote:

> Another convenient feature of the Kachina is output power controllable to
> within 0.1 db of the indicated value. I use this feature as an attenuator
> test generator to evaluate and calibrate wattmeters. For example, the
> wattmeter in my MFJ 989C is right on at 10 watts up to 100 watts, to within
> a pointer width, but has increasing error below 10 watts. The QRP level of
> 5 watts actually is indicated at 7.5 - 8 watts on the meter scale.

I find the meter on my MFJ 989C is more an indication of "ya, it's
transmitting but, don't ask me how much power buddy!"

Comparing it to the inidcations on the TS2000 and the measurements from
the Bird AND an RF Applications VFD, here is the breakdown:

TS2000	BIRD	VFD	MFJ-989C
--------------------------------
5	7	7	6
6	7	7	7
7	8	8	8
8	10	10	8
9	11	11	10
10	13	13	15
11	13	13	15
12	14	14	15
13	14	14	15
14	16	16	18
15	16	16	20

At higher powers, it becomes insanely inaccurate.

622w indicated on the VFD (and I trust this meter) shows as just under
500w on the MFJ 989C.

I think that the tuner, other than showing up in "kit" form with parts
rattleing around inside the case, works pretty good but, the inclination
that the meters on the thing provide anything close to a true indication
of power at levels above about 25w is laughable.

> 
> I know none of this applies to the Elecraft products, but I just wanted Bob

Same here.  Just wanted to put my 2cents worth out about the accuracy of
the 989C meters.

73 de John kc4kgu